At Writers' Block in Columbus I installed a no-repeat rule for the whole season a few years ago. inthe past poets have talked me in and out of allowing repeats in grand slams, and our 2010 NPS allowed it. As of 2011 I'll be switching it back to no-repeats all the way through. This rule is true through all of our slam seasons (WOW and iWPS). Just as important as craft (here anyway) is the show. My audience is pretty faithful and supportive year-round, and they don't want to see repeating work more than they have to, and the more competitive folks appreciate that a poet can't rely on old poems in front of a newbie audience judge to get over.
Finally, and most notably, we've been running a show called "First Draft" for about four years now. It is the only ongoing mic anywhere to my knowledge that ONLY offers never-performed work...demands it, in fact: in the open mic, from the feature....all the way through the show. We've had notable features for this show and they've embraced the opportunity to come and do work that isn't their typical hits. That show by itself is pretty priceless (and distinctly ours).
Anyhow, I applaud any show that makes the ongoing pursuit of growth in its artists a priority. Kudos to your poets, Shaggy!